Bilingualism and aging: Costs and beneﬁts
In previous papers we have suggested that many aspects of cognitive development and cognitive aging can be described in terms of the interplay between knowledge representations and cognitive control (Craik & Bialystok, 2006, 2008). One obvious diﬀerence between the cognitive changes observed in childhood and during aging is that in childhood both representational knowledge and control of that knowledge are growing in eﬃciency and complexity, whereas in aging control declines but knowledge remains relatively intact (Craik & Bialystok, 2008; Light, 1992). Although knowledge representations remain “available” in old age, in the sense that they still exist in the older person’s brain, access to that knowledge is typically impaired unless the information is retrieved and used on a regular basis. Everyday examples include diﬃculties experienced in recollecting names of people and details of events that the older adult has not thought of for some time. In the laboratory, such age-related problems of accessibility may be illustrated by slower recognition latencies, lower word ﬂuency and category generation scores, and the relatively greater deﬁcit in recall relative to recognition (Craik & Jennings, 1992; Light, 1992). With regard to the age-related decline in control processes, many studies have shown that working memory abilities fall oﬀ with increasing age (e.g., Park et al., 2002), as does inhibitory control (Hasher, Zacks, & May, 1999), task-switching performance (Meiran & Gotler, 2001), and other aspects of executive control (Daniels, Toth, & Jacoby, 2006).